Response to chemotherapy of human,malignant melanoma xenografts in athymic,nude mice

In attempts to elucidate the factors determining individual differences in response of tumors to chemotherapeutic agents, the sensitivity of six human malignant melanomas growing in athymic, nude mice was studied. Six agents, viz. DTIC, CCNU, vinblastine, procarbazine, as well as the toxic lectins abrin and ricin, were administered in maximum tolerable doses to the tumor-bearing mice. The response to treatment was expressed as tumor growth delay, i.e. the number of volume doubling times saved by the treatment. The xenografts had very nearly retained the morphology of the parent tumors and were histologically similar. They showed different and characteristic early growth rates and also wide variations in their response to the agents tested. Unexpectedly, in the case of DTIC, CCNU and procarbazine, the response of the xenografts proved to be inversely related to the early growth rates of the tumors. For vinblastine, abrin and ricin, no correlation between response and growth rate of the tumors was apparent. Procarbazine had the best overall effect among the agents here tested. DTIC, CCNU and vinblastine had somewhat less and about equal overall efficiency. The plant toxin abrin, which acts by inhibiting protein synthesis, was at least as effective as DTIC. When abrin was given together with DTIC, the effect on the two xenografts tested was superior to that of each agent given alone. The wide variations observed in the response of the histologically similar xenografts to the different agents demonstrate that testing of the chemosensitivity of human xenografts requires the use of a panel of tumors of each histological type. The clear relationship found between the early growth rate of the xenografts and their sensitivity to three of the drugs most commonly used in the treatment of malignant melanomas, may have clinical implications.     

The monoclonal antibody SM5-1 recognizes a fibronectin variant which is widely expressed in melanoma

Background  

Previously we have generated the monoclonal antibody SM5-1 by using a subtractive immunization protocol of human melanoma. This antibody exhibits a high sensitivity for primary melanomas of 99% (248/250 tested) and for metastatic melanoma of 96% (146/151 tested) in paraffin embedded sections. This reactivity is superior to the one obtained by HMB-45, anti-MelanA or anti-Tyrosinase and is comparable to anti-S100. However, as compared to anti-S100, the antibody SM5-1 is highly specific for melanocytic lesions since 40 different neoplasms were found to be negative for SM5-1 by immunohistochemistry. The antigen recognized by SM5-1 is unknown.     

Establishment and characterization of human uveal malignant melanoma xenografts in nude mice

The purpose of this study was to develop a suitable animal model for the investigation of the pathogenesis and therapy of uveal malignant melanoma. Eight choroidal malignant melanomas from eight patients were transplanted into nude mice in an attempt to establish a serially transplantable tumour model. Tumour tissue blocks (2 x 2 x 2 mm) from enucleated eyes with choroidal malignant melanoma were transplanted subcutaneously into the flanks of nude mice. The growing tumours were measured and serially transplanted. The tumour samples were investigated by histology, immunohistochemistry and electron microscopy. Only one of the eight transplanted primary tumours (13%) was established as a xenograft in nude mice. Furthermore, the take rate of the transplantable tumour was low (13%). The growth of the tumour fitted a Gompertz function, and the calculated tumour volume doubling time was 54 days. The transplanted tumour cells were epithelioid and slightly larger than the primary tumour cells and had prominent nucleoli. However, the transplanted tumour retained a morphological appearance similar to that of the primary tumour. Immunohistochemical examinations demonstrated that the cells preserved the characteristic properties of malignant melanoma. However, the transplanted cells demonstrated vimentin reactivity, whereas the primary tumour cells were negative for vimentin. It can be concluded that a new experimental model of malignant uveal melanoma with tumours that were easy to observe and access was established in nude mice.     

Photodynamic therapy of human malignant melanoma xenografts in athymic nude mice

While photodynamic therapy (PDT) for cutaneous malignancies including dermal recurrences of breast cancer and basal cell carcinomas has shown great promise, PDT of malignant melanoma has remained incompletely understood. A comparison study of the effects of PDT on human xenograft amelanotic and melanotic malignant melanoma in the athymic nude mouse model was performed. Twenty-four hours after ip administration of Photofrin II, the responses to total laser light doses of 25-300 J/cm2 were evaluated by histologic examination. Animals were also sacrificed 24 hours after administration of Photofrin II without light, and their uptake and localization of hematoporphyrin derivative (HpD) for each tumor were measured and compared. The results indicate that human xenograft melanotic melanoma, despite the fact that it contains more HpD than does amelanotic melanoma, is far less responsive to PDT. This result appears to be due to the competing chromophore melanin, which may inhibit the photochemical reaction at several key points.     

Establishment and characterization of a human melanoma cell line (MV3) which is highly metastatic in nude mice

To select human melanoma cells that are highly tumorigenic and metastatic in nude mice we have implanted fragments of a fresh human melanoma metastasis subcutaneously (s.c.) into a nude mouse. After 3 passages in nude mice, part of the xenograft was cultured and a new melanoma cell line, MV3, was established. After intravenous (i.v.) inoculation of 2 x 10(6) MV3 cells, 95% of the nude mice (n = 20) developed lung colonies within 6 weeks. S.c. inoculation of 2 x 10(6) MV3 cells resulted in 95% tumor take, while 90% of the mice (n = 20) showed spontaneous metastases in the lungs within 7 weeks. Histological and immunohistological features of the original tumor of the patient were largely retained in the tumors of the mice and in the cell line in vitro. As shown by Alcian blue staining, MV3 cells contain large quantities of glycosaminoglycans (GAGs) and/or proteoglycanes (PGs), both in vivo and in vitro. The cells showed a marked expression of transferrin receptor, ICAM-1, EGF-receptor, and VLA-2 integrin. As only few human melanoma cell lines are available that frequently show metastasis in nude mice, the highly metastatic MV3 cell line represents a useful tool for studying the expression and regulation of molecules on human melanoma cells involved in the process of metastasis.     

Progression markers in metastasizing human melanoma cells xenografted to nude mice (review)

The past decade transplants of human tumors in nude mice have been increasingly used as an experimental model for local tumor growth and dissemination. A few human melanoma cell lines have been described that give rise to metastases in nude mice after subcutaneous inoculation. First we give an overview of some relevant literature with respect to the pathogenesis of tumor metastasis, models to study human cancer metastasis, neoplastic progression and the detection of antigens involved in metastasis. Finally we describe our results concerning the morphological and immunohistochemical profile of six different human melanoma cell lines and their xenograft lesions in nude mice using a set of monoclonal antibodies recognizing different categories of human melanoma-associated antigens. From the data we conclude that the nude mouse mouse model appears suitable to study the role of melanoma-associated progression markers in the pathogenesis of metastasis.     

Extrapulmonary, tissue-specific metastasis formation in nude mice injected with FEMX-I human melanoma cells

FEMX-I human malignant melanoma cells, originating from a lymph node metastasis in a patient, uniquely and selectively produced extrapulmonary metastases after i.v. injection of cells prepared from xenografts into adult, nude mice. After a lag time of approximately 50 days, metastases were observed in s.c. sites at the back and front of the neck, and in axilla and inguinal regions. Tumor colony formation in lungs were never detected. The interscapular tumors showed a close relationship to brown fat, partly infiltrating this tissue, whereas the other s.c. tumors seemed to be localized to lymph nodes. Mesenterial and mediastinal lymph node metastases were frequently found, together with retroperitoneal tumors along the spine. The normal cells of the adrenal medulla were often replaced by melanoma cells, whereas the cortical tissue was not affected. The conclusion that FEMX-I cells possess an inherent ability for tissue-specific metastasis formation is supported by the metastatic pattern seen after i.p. and intrasplenic injection, as well as after inoculation of the cells in the footpads of the mice. The relatively slowly growing FEMX-I tumors showed the same differentiated morphology as the patient's tumor, independent of the site of growth and the number of passages in the animals. The FEMX-I tumor was easily established as a cell line in vitro. Such cells showed a strongly reduced metastatic capacity, indicating that the in vitro growth conditions had induced alterations in the FEMX-I cells influencing their ability to form site-specific metastases, changes that were shown to be reversible. It is suggested that structures on the surface of the tumor cells, as well as growth factors in the host tissues, may be of importance for the observed tissue specificity. The FEMX-I melanoma, which, as a human tumor in nude mice, has a unique metastatic pattern, offers possibilities for investigating mechanisms involved in site-specific metastasis formation, as well as for testing effects of antimetastatic, chemotherapeutic, and immunotherapeutic agents against human extrapulmonary micro- and macrometastases.     

A human melanoma line heterogeneous with respect to metastatic capacity in athymic nude mice

The ability of the human A375 melanoma cell line to produce experimental and spontaneous in young BALB/c nude mice was examined. Cloned lines, obtained by isolation in semisolid agar, differed significantly (4/10 cloned lines examined, P less than or equal to .005) from the parent tumor line with regard to their ability to form lung tumor nodules subsequent to iv injection. Lines established from such lung tumor nodules were more metastatic than the parent line following both iv and sc injection. These results show that the human melanoma cell line used in these studies contained cells with diverse metastatic potential and suggest that metastasis in the nude mouse results from the preferential selection of metastatic subpopulations.     

Interactions with host macrophages and ability of human melanoma cell lines to grow in nude mice

The interactions of nude mouse macrophages with five human melanoma cell lines, characterized by their resistance to mouse NK activity and varying in their ability to grow s.c. in nude mice, were investigated. These lines were equally susceptible in vitro to both cytostatic and tumoricidal activities of activated peritoneal macrophages collected from nude mice inoculated 3 days previously with Brucella abortus B19R strains. I.p. injection of a poorly tumorigenic melanoma cell line (PTCL) in nude mice was followed by the local appearance of macrophages able to kill these cells in a 48-hr 3H-thymidine cytotoxicity assay. The level of tumoricidal macrophages was maximum for the first week and then slowly declined to disappear by the 4th week following PTCL inoculation. The use of an HTCL instead of a PTCL also induced macrophages able to kill HTCL cells, but the cytotoxicity level was lower and the activity disappeared more rapidly. In cross-experiments using PTCL-activated macrophages as effectors on HTCL targets, these cells were found to be less sensitive than PTCL cells when macrophages were taken at weeks 2 and 3 following PTCL inoculation. To investigate whether tumoricidal macrophages activated in vivo with human melanoma cells could also act in vivo, we inoculated these s.c. into nude mice, simultaneously with live HTCL cells. Peritoneal cells rich in melanoma-activated macrophages prevented HTCL growth in most recipients, whereas spleen cells from the same donor mice did not modify the tumor take. These data indicate that xenogeneic tumors could activate nude mouse macrophages in vivo and suggest that the ability of human tumors to grow in nude mice could be related to their capacity to activate host macrophages locally and to the susceptibility of human tumor cells to the tumoricidal activity of activated macrophages.     

A new experimental metastasis model in athymic nude mice, the human malignant melanoma LOX

The human tumor line LOX was established as an s.c. xenograft in nude mice from a lymph-node metastasis of a patient with malignant melanoma. I.v. injection into adult nude mice of single-cell suspensions prepared from xenografts resulted in progressively growing lung tumor colonies that killed the animals. No difference in colony formation was seen between cells taken from lung colonies and s.c. xenografts. An in vitro cell line, LOX-L, was established from lung colonies, and the monolayer cells, detached with EDTA, retained the same ability to form experimental lung metastases. In a total of 14 experiments, 82 of 89 mice receiving 1 X 10(6) viable tumor cells died with a mean survival time of 34.1 +/- 4.8 days. Long-term passaging in vivo and in vitro did not result in any alteration of the lung-colonizing potential of the LOX cells, whereas trypsinization of the cells before i.v. injection reduced lung colony formation. The life span was inversely related to the number of LOX cells injected, permitting estimation of the cell kill caused by chemotherapy. Mice injected i.v. with the LOX cells showed the same relative response to cis-diamminedichloroplatinum (CDDP) and mitozolomide (MZA) as did animals carrying s.c. xenografts. The LOX cells have shown a remarkable stability and similarity to the cells of the patient's tumor with respect to morphology, karyotype and chemosensitivity. The LOX model may be useful for testing effects of therapy on lung micro- and macrometastases, and the activity of antimetastatic agents, as well as for studying mechanisms involved in the metastatic process.     

Enhanced tumorigenicity, melanogenesis, and metastases of a human malignant melanoma after subdermal implantation in nude mice

Transplantation of human tumors into the organ or tissue of their origin (orthotopic transplantation) in nude mice can result in significant enhancement of tumor growth and metastases, compared with sc (ectopic) transplantation. Because melanocytes are normally found in the epidermal-dermal junction, intradermal inoculation of melanoma cells might be expected to improve their potential for malignant growth as xenografts. The purpose of our study was to examine this possibility. We found that because mouse epidermis and dermis are so thin, it was not possible to inject a bolus of tumor cells intradermally; instead the cells were actually deposited in the most superficial layer of the subcutis (i.e., subdermally). We evaluated the behavior of cells from a human melanoma cell line after sc or subdermal inoculation into National Institutes of Health Swiss athymic nude mice. The cells used were from (1) the predominantly amelanotic human malignant melanoma cell line MeWo, originally established from a melanotic lymph node metastasis, and (2) two MeWo variants resistant to wheat germ agglutinin (WGAr), which were selected for altered malignant capacities. Whereas 5 X 10(5) MeWo cells were required to achieve 100% tumor take with sc injection, only 2 x 10(4) cells were required with subdermal inoculation. Subdermal injection of the MeWo cells resulted in the development of highly melanotic and nonencapsulated primary tumors, which grew quickly into the dermis and epidermis and metastasized at high frequency to draining lymph nodes. In contrast, the tumors that developed after sc injection were found in the deepest layer of the subcutis and were predominantly amelanotic and encapsulated; they rarely metastasized to lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Invasive pattern of lac-Z-transfected human glioblastoma cells in nude mice brain

Primary, malignant brain tumors show an extensive infiltrative invasion into surrounding normal brain. At present, little information is available regarding the local invasive behavior of human brain tumors and until now no animal model suitable to mimic human gliomas has been reported. To identify the infiltrative behavior of an established glioblastoma cell line (SNB19), we achieved a stable transfection of the SNB19 cell line with β-galactosidase (lac-Z) plasmid. The stable β-galactosidase-expressing cells were then injected intracerebrally into nude mice in an attempt to follow its pattern of spread. The mice were sacrificed at 3, 4, and 6 weeks postinjection. We could detect tumor formation in all of the animals, and the tumor size increased gradually over the 6 week time period. Three weeks after injection, tumor cells showed characteristic infiltrative invasion along the corpus callosum. We also observed tumor-cell invasion into the anterior commissure in some animals, and each tumor cell could be identified by lac-Z expression as visualized by its blue color. Further invasion was identified at 4 and 6 weeks postinjection. Our results suggest that this model could be used to study the molecular mechanisms involved in the invasion of gliomas so that appropriate therapeutic intervention strategies could be designed.     

Growth inhibition of human melanoma tumor xenografts in athymic nude mice by swainsonine

Swainsonine, an inhibitor of alpha-mannosidases, has been shown to block experimental metastasis of B16F10 melanoma and MDAY-D2 lymphoid tumor cells in syngeneic mice. In this report we demonstrate that swainsonine also reduces the growth rate of human melanoma cells in vitro and in vivo. Graded doses of swainsonine were administered either orally or via implanted Alzet miniosmotic pumps to athymic nude mice bearing subcutaneously implanted human MeWo melanoma cells. Swainsonine at 10 micrograms/ml in the drinking water or 0.5 mg/kg/day administered by miniosmotic pump reduced the growth rate of the MeWo tumors by approximately 50% and inhibited the expression of complex-type oligosaccharides in tumors and host intestine by only 10-20%. Swainsonine doses of 4 mg/kg/day reduced expression of complex-type oligosaccharides by 85% in vivo but afforded no additional inhibitory effect. A glycosylation mutant of MeWo called 3S5 has a defect in the synthesis of complex-type asparagine-linked oligosaccharides resulting in incomplete processing similar to that observed in swainsonine-treated MeWo tumor cells. Swainsonine did not inhibit the proliferation of 3S5 cells in vitro nor the growth of 3S5 tumors in nude mice. The results suggest that expression of highly branched complex-type oligosaccharides commonly associated with the malignant phenotype may provide the tumor cells with a growth advantage.     

Radiosensitivity of nall human melanoma transplanted into nude mice: Repair,reoxygenation and dose fractionation

Split dose and fractionated γ-rays experiments have been performed on a human melanoma transplanted into nude mice using an in vitro colony assay. Repair of potentially lethal damage observed after a single dose of 20 Gy was found to no longer occur when 7 daily doses of 2.5 Gy were administered. In split-dose experiments, the increase in survival level probably can not be explained by repair of sublethal damage. When a single high dose of radiation is administered a certain reoxygenation is observed; however there is no reoxygenation when low radiation doses are delivered daily.     

Nuclear factor-kappaB activity correlates with growth, angiogenesis, and metastasis of human melanoma cells in nude mice.

The purpose of this study was to determine the role of nuclear factor (NF)-kappaB/relA activity in the induction of angiogenesis and production of metastasis by human melanoma cells. Highly metastatic melanoma variant cells expressed high levels of constitutive NF-kappaB activity. Transfection of highly metastatic human melanoma variant cells with a dominant-negative mutant inhibitor of nuclear factor-kappaB alpha (Ikappabeta alpha) expression vector (Ikappabeta alphaM) decreased the level of constitutive NF-kappaB activity, inhibited s.c. tumor growth, and prevented lung metastasis in nude mice. Furthermore, the slow-growing s.c. tumors formed by the IkappaB alphaM-transfected cells exhibited a decrease in microvessel density (angiogenesis), which correlated with a decrease in the level of interleukin-8 expression. Collectively, these results demonstrate that NF-kappaB/reLA activity significantly contributes to tumorigenicity, angiogenesis, and metastasis of human melanoma cells implanted in nude mice.     

Inhibition of the growth of human melanoma xenografts in nude mice by human tumor-specific cytotoxic T-cells

Melanoma-specific T-cells (CTLs) are specifically cytotoxic for autologous tumor, when assayed in vitro. To examine their effectiveness in vivo, we tested the ability of these human T-cells to inhibit growth of human melanoma xenografts by using a Winn assay. Nude mice receiving specific CTLs (n = 10) demonstrated a dramatic inhibition of tumor growth. All treated mice were tumor-free at day 50 and nine remained tumor-free at day 65, vs. control mice (n = 10) with average tumor volumes of 321 mm3 and 808 mm3, respectively. To control for the possibility that a non-specific response to the human T-cells could inhibit tumor growth, an additional group received allospecific CTLs. There was no inhibition of tumor growth in this group (n = 8), with the average tumor volume of 2,768 mm3 at day 40 vs. 1,882 mm3 in the control group (n = 10). We conclude that these tumor-specific CTLs can inhibit tumor growth in vivo and may prove useful in the adoptive immunotherapy of melanoma.     

Acidic extracellular pH promotes experimental metastasis of human melanoma cells in athymic nude mice

Extracellular pH (pH(e)) is lower in many tumors than in the corresponding normal tissue. The significance of acidic pH(e) in the development of metastatic disease was investigated in the present work. Human melanoma cells (A-07, D-12, and T-22) were cultured in vitro at pH(e) 6.8 or 7.4 (control) before being inoculated into the tail vein of BALB/c nu/nu mice for formation of experimental pulmonary metastases. Cell invasiveness was studied in vitro by using Matrigel invasion chambers and angiogenesis was studied in vivo by using an intradermal assay. Protein secretion was measured by ELISA and immunocapture assays. Cells cultured at acidic pH(e) showed increased secretion of proteinases and proangiogenic factors, enhanced invasive and angiogenic potential, and enhanced potential to develop experimental metastases. Acidity-induced metastasis was inhibited by treatment with the general matrix metalloproteinase (MMP) inhibitor GM6001, the general cysteine proteinase inhibitor E-64, or blocking antibody against vascular endothelial growth factor-A (VEGF-A) or interleukin-8 (IL-8). Our study indicates that acidic pH(e) promotes experimental pulmonary metastasis in A-07, D-12, and T-22 human melanoma cells by a common mechanism involving acidity-induced up-regulation of the proteolytic enzymes MMP-2, MMP-9, cathepsin B, and cathepsin L and acidity-induced up-regulation of the proangiogenic factors VEGF-A and IL-8. One consequence of this observation is that treatment strategies involving deliberate tumor acidification to improve the efficacy of chemotherapy, photodynamic therapy, and hyperthermia should be avoided. Moreover, the possibility that the pH(e) of the primary tumor may be an important prognostic parameter for melanoma patients merits clinical investigation.     

Control of human melanoma growth in nude mice by autologous allo-activated peripheral blood lymphocytes

Human peripheral blood lymphocytes (PBL) were activated in vitro by means of a pool of allogeneic PBL from normal donors and then evaluated for in vivo activity against human melanoma cells xenografted in splenectomized and irradiated athymic (nude) mice. The subcutaneous (s.c.) growth of human melanoma cells was inhibited by intravenous (i.v.) injection, 2 hr later, of such allo-activated, autologous and allogeneic PBL in 7/8 and in 6/9 mice respectively. Unstimulated PBL were ineffective. When allo-activated patients' lymphocytes were administered 3 days after s.c. implantation of autologous melanoma cells, inhibition of tumor growth was observed in 1/6 mice. A significant delay in tumor appearance was noted in the remaining animals. Unstimulated as well as allo-activated, lymphokine-releasing helper-enriched human PBL had no effect on melanoma xenografts, indicating that the tumor inhibition by tumor-cytotoxic allo-activated PBL was not due to recruitment of murine immuno-competent cells by human lymphokines. These results indicate that allo-stimulated, tumor-cytotoxic human PBL given i.v. to nude mice can circulate and inhibit the growth of autologous or allogeneic human melanoma cells implanted s.c.